2623818 (http://support.microsoft.com/kb/2623818 / ) The IM history is not stored in the default Exchange mailbox when you use Lync 2010

2639837 (http://support.microsoft.com/kb/2639837/ ) "An error occurred during the online meeting." notification when a user tries to join an online meeting that is created in Outlook by using Lync 2010

2623813 (http://support.microsoft.com/kb/2623813/ ) An update is available to apply certain changes on the "Set Location" feature in Lync 2010